package com.just.fun.annotation;

public class S1 {
//    private static S1 s1=new S1();
//    private S1() {
//    }
//    public static S1 getInstance(){
//        return s1;
//    }
     private volatile static S1 s1=null;
     private S1(){}
     public static S1 getInstance(){
         if(s1==null){
             synchronized (s1){
                 if(s1==null){
                     s1=new S1();
                 }
             }
         }
         return s1;
     }
}
